The cardiac valve mainly refers to the left atrioventricular valve, the right atrioventricular valve, the pulmonary valve and the aortic valve. The tricuspid valve of the right atrioventricular orifice comprises three triangular-like cusps or segments, and their bases are attached to a fibrous ring surrounding the atrioventricular orifice; the fibrous ring, the valve, the chordae tendineae and the papillary muscle are regarded functionally as a tricuspid valvar complex. The fibrous ring of the left atrioventricular orifice, the mitral valve, the chordae tendineae and the papillary muscles are an integral entirety functionally and structurally, and are referred to as a mitral valve complex. The aorta is located at the center of the fibrous skeleton of the heart. Three semilunar aortic valves leaflets are attached on the tissue ring constructed by dense connective tissues. The pulmonary valve is located at the left front of the aortic valve, and the pulmonary valve annulus is attached on the trunk of the pulmonary valve; commonly, there are three connected valve annulus, that is, the front curved valve annulus, left curved valve annulus and right curved valve annulus. During the life of a human being, the natural cardiac valve can repeatedly open and close for more than 2700 million times.
AS (Aortic Stenosis) or PS (Pulmonary Stenosis) is one of the common valvular diseases. For a long time, aortic valve replacement is known as the only long-term and effective treatment. Thanks to continuous innovations of cardiac intervention methods and medical devices, PAVR (Percutaneous Aortic Valve Replacement,) has gradually become the mainstream of surgery. How to accurately and firmly position the implant is one of the key factors for a successful surgery.
However, function insufficiency of the mitral valve and tricuspid valve is one of the most common heart diseases, such as the tricuspid valve insufficiency caused by high pressure of pulmonary artery and physiological expansion of the tricuspid valve, the mitral valve insufficiency or the tricuspid valve insufficiency caused by diseases accompanied by prolapse of the mitral valve or prolapse of the tricuspid valve, and tricuspid stenosis or mitral stenosis caused by valve damages resulted from rheumatic inflammation.
Among patients with mitral valve insufficiency, there are about 2 million to 2.5 million people in the United States suffering from mitral regurgitation, and it is expected that the number of the patients will rise up to 4.8 million in 2030, and the incidence rate of the disease in China is about 0.5% to 2%. In the United States and other western developed countries, the mitral valve insufficiency is mainly caused by mucinous degenerative diseases, which accounts for about 45% to 65%. In many developing countries, rheumatic lesion is the main reason of mitral valve diseases, which accounts for about 80% (Zhang Baoren, Xu Zhiyun, chief editors, Cardiac Valve Surgery [M], People's Medical Publishing House, 2007, 478-488). Mitral regurgitation can be divided into three types, that is, functional, degenerative or mixed mitral regurgitation. Functional mitral regurgitation and degenerative mitral regurgitation are most common Functional mitral regurgitation is usually secondary to impaired motion function of the left ventricular wall, left ventricular expansion or function disorder of the papillary muscles, and is common among patients with heart failure. Some of the patients suffer from ischemic mitral regurgitation secondary to coronary heart disease or suffer from mitral regurgitation related with nonischemic cardiomyopathy. The degenerative mitral regurgitation is commonly regarded as pathological changes of valve structure or pathological changes of subvalvular structure, which comprises the abnormal extension or fracture of the chordae tendineae.
Traditional therapy of cardiac valve disease includes drug therapy for mild illness and surgery methods for illness with corresponding surgery indications. Among which, the typical thoracotomy and open heart surgery are too invasive, which need to establish an extracorporeal circulation, and have higher incidence of complications and risk of infection. In order to reduce the risk of surgery, Percutaneous Annuloplasty, Percutaneous Valve Replacement, and Percutaneous valve Repair are developed. In all of these methods, there exist problems that the positioning between the cardiac valve implant and the autogenous tissue is inaccurate and the anchoring is not firm.
In order to solve the problems above, Chinese patent No. CN201120022195.1 provides an ascending aorta endovascular exclusion stent with a filled type fixing capsule. The filled type fixing capsule is stitched or adhered to the outer side of the coated cylindrical stent. The capsule is filled with water absorptive material, which is water-swellable in the blood vessel, thereby fixing the stent and preventing displacement. However, according to this patent, the tube diameter of the delivery sheath is limited by the fixing capsule.
The U.S. patent application with pub. No. US2010280606A1 describes a valve prosthesis adapted to operate in conjunction with native heart valve leaflets. The valve prosthesis comprises a frame, and the frame is hollow. The anchor portion can slide in the hollow frame under the push of the delivery system so as to pierce the tissue. The diameter of the tail section of the anchor portion is greater than the internal diameter of the hollow frame, which can perform the function of fixing the frame and the tissue. However, the anchor portion, whether it is released or not, is one part of the valve prosthesis, and, when the anchor portion is pushed, it will be limited due to the shape of the frame and limited by the forces exerted by the frame.
The U.S. Pat. No. 8,579,964B2 and the Chinese patent No. CN103079498A disclose a method of anchoring a prosthetic valve in a patient's heart. Said method comprising: providing the prosthetic valve, wherein the prosthetic valve comprises an anchor having an atrial skirt, an annular region, a ventricular skirt, and a plurality of valve leaflets, wherein the anchor has a collapsed configuration for delivery to the heart and an expanded configuration for anchoring with the heart. The anchor disclosed by the patents comprises anchoring tabs which are combined with the implanted prosthesis, and the anchor can be provided with barbs. However, according to the anchoring method of the patents, the atrial skirt and the ventricular skirt will damage the structures of the patient's annulus and valve themselves, so the method is only applicable to valve replacement.
The U.S. patent applications No. US2005107811A1 and No. US2008058868A1 disclose an anchoring system and a delivery method thereof, wherein the anchor is made of shape memory alloy, and the anchor has two curved legs that cross in a single turning direction to form a loop. The anchor can assume different configurations such as a deployed configuration and a delivery configuration, and the anchor may switch between these two different configurations. In operation, the anchor may be released from a delivery configuration so that the shape memory alloy self-expands into the deployed configuration, so that the two legs of the anchor may penetrate the tissue in a curved pathway to fix the tissue. According to the anchoring system and the delivery method thereof, the legs of the anchor penetrate the tissue only under the forces of the shape memory alloy during its deployment, for some penetrating positions such as those in the tough tissue, for example, in the endocardium, the piercing forces may not be large enough, as a result, the anchor easily falls off in the process of piercing, and after it is pierced into the tissue, the anchor is not fixed stably and easily falls off.
The current clinical findings show that the techniques described above can take some effects on anchoring and on interventional therapy for valvular heart diseases, but there is still not a satisfactory implant with anchoring device for heart valve disease in the prior art, which can realize accurate positioning and firm anchoring of the functional cardiac valve prosthesis at the position where the therapy is required.